Ensoniq ESQ-M to SQ80-M Conversion Kit

Assembly Guide

Disclaimer

The information and methods described herein are provided “AS-IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED. Use the concepts, examples and information at your own risk. There may be errors and inaccuracies, that could be damaging to your devices. Proceed with caution, and although it is highly unlikely that accidents will happen because of following advice or procedures described in this document, the author does not take any responsibility for any damage claimed to be caused by doing so.

Introduction

This assembly guide assumes some basic soldering skills on the part of the reader. While the kit is made to be relatively easy to assemble, prior DIY experience is recommended. This guide is a step-by-step explanation of how to properly assemble and install the SQ80-M Kit.

Note: This guide assumes that the waveroms are socket-mounted in the original ESQ-M unit. If that is not the case, then some extra work is required: both roms must be desoldered first, and sockets added.

There are 9 steps in total. All pictures can be clicked for larger versions.

The kit

The first thing to do is familiarize yourself with the kit and its components, as shown here:

2 piggy-back adapter PCBs (surface mount device will be preassembled)

2 4-pin PCB connector headers

2 14-pin PCB-to-socket headers

2 20-pin PCB-to-socket headers

1 32-pin DIL IC socket (actual socket form factor might differ)

1 40-pin DIL IC socket (actual socket form factor might differ)

1 27C020 EPROM (preprogrammed with SQ80 waverom data)

1 27C256 EPROM (preprogrammed with SQ80-M OS)

1 jumper wire

1 4-wire cable

Assembly and installation will only require a soldering iron and an IC extractor.

Step 1

The most delicate step of the assembly is soldering the PCB-to-socket headers. They are mounted on the underside of the PCBs (location is displayed on the silkscreen, see the following picture), and soldered on top. The 14-pin headers go on the WAVEROM PCB, while the 20-pin headers go on the DOC PCB.

This next picture shows the correct way to install the headers: the plastic part is mounted against the PCBs, the wide metal base of the pins protrudes outwards.

In order to ensure that the headers will be properly perpendicular to the PCBs, an easy trick is to use the provided sockets as temporary holders: simply let the PCB and headers rest on top of the socket. DO NOT insert them all the way through: it is not necessary and will be a bother to take apart later.

The headers might have a tendency to “belly-down” a little, as shown on the following picture (the 20-pin headers are more prone to this).

A simple workaround for this is to start by soldering a middle pin, applying gentle pressure on the PCB to make it perfectly flush with the headers. Once that is done as shown on this picture, and after checking again for proper perpendicularity, the other pins can be soldered with confidence.

Step 2

The PCBs should now look like this, seen from the top:

The next step is to mount the IC sockets on the PCBs: the 32-pin socket belongs to the WAVEROM PCB, while the 40-pin socket goes on the DOC PCB.

Note: Pay special attention to the socket orientation: they have a notch that must be aligned with the notch represented on the PCB silkscreen, highlighted in red on the next picture.

Step 3

Moving on, it’s time to add the PCB connector headers. The shorter side of the pins is to be soldered to the PCBs, the longer part being meant to receive the connectors:

Step 4

Finally, we add the jumper wire for SA15. In the pictures I mounted it below the PCB and soldered it on top, but it doesn’t really matter.

This completes the assembly of the PCBs. The device is now almost ready, all that’s left to do is to install the kit into the ESQ-M, as will be detailed in the next steps.

Step 5

The next operations must be conducted on an unplugged unit.

After opening the unit, the original waveroms (U13/U16), the original OS EPROM (U14) and the DOC (U21) must be extracted from their sockets. The next pictures are taken with the front panel of the unit toward the bottom of the image.

Note: Again, pay attention to the ICs orientation: see the notches highlighted in red on the following picture. This orientation must be properly respected in the following steps.

Note: It is easier to unplug the power connector J6 for this operation. Pay VERY CLOSE attention to its orientation, a mis-wiring when reconnecting it will DESTROY the unit.

As this connector is not keyed, I recommend marking the position of the connector on both the male and female sides with a marker line prior to unpluggin.

This picture shows the empty sockets. Notice how they also have an orientation notch, which is also printed on the mainboard silkscreen.

Step 6

Next, we install the piggy-back PCBs into their respective sockets:

WAVEROM can go in either of the original wave sockets (U13/U16).

DOC goes in the DOC socket (U21)

Note: This is a crucially delicate step: the PCBs must be correctly inserted in the target sockets, with no pin overhanging past the sockets.When properly inserted, both PCBs will be perfectly aligned with each other, as highlighted in red in the picture. Furthermore, on the PCBs the row of pins closest to the rear panel of the ESQ-M will also be perfectly aligned with the last row of pins of the mainboard socket.This doesn’t show very well in this picture due to perspective artifact, but see the previous picture for reference: the red line illustrates the expected alignement.

Once you have made sure that their alignment is correct, press firmly on the piggy-back PCBs to ensure they are properly seated in their receiving sockets. Do not stop at the first resistance: make absolutely sure the PCBs are all the way down into the sockets. Use two fingers (thumb and index) to provide even downforce. This is important to prevent the PCBs from popping back up.

Note: While I do not recommend it, if you want to make absolutely sure the PCBs will not pop back up on their own, you can add a bit of hot glue on e.g. two corners. It will still be reversible (reheat the glue).

Note: This bears repeating, but it is crucial to mind the orientation of these chips and insert them with their notch in the correct position.

Press firmly on all ICs to ensure that they are properly seated in their sockets.

Step 8

The penultimate step of the installation process is to solder the free end of the jumper wire to collect the SA15 signal.
This wire must be soldered on the leg of resistor R29 closest to the front panel of the ESQ-M, as seen in this picture:

Step 9

Here comes the final step: connect the two piggy-back PCBs together with the provided 4-wire cable. The cable connectors are not keyed, you must ensure that the cable is connected in a straight way, with pin 1 of the WAVEROM XC connector wired to pin 1 of the DOC XC connector and so on, as highlighted on the picture.

That’s it, it’s now time to plug the power connector back and…

BE VERY VERY CAREFUL WHEN PLUGGING THIS CONNECTOR BACK! IT IS NOT KEYED, IF IT IS MISPLACED (OFFSET) BY EVEN ONE PIN (A VERY EASY MISTAKE), YOU WILL FRY, I REPEAT _YOU WILL FRY_ YOUR UNIT. YOU HAVE BEEN WARNED.

…and close the unit, perform a Memory Reset and finally enjoy your brand new SQ80-M!